H.264 MP4 playback issues relative to Apple Compressor

Description

Summary of the bug: FFmpeg H.264 MP4 movies don't play as well as similar movies encoded with Apple Compressor.

How to reproduce: Create an H.264 MP4 from FFmpeg, and another using Apple Compressor. Then play the movies in QuickTime? player or VLC. The Apple version generally maintains frame rate much better than the FFmpeg version.